Both son and dad were home safe after spending four hours at UMass Memorial Medical Center — University Campus in Worcester. They were treated for hypothermia.

Fighting to keep above water, the father and son reached out to the ice in front of them, to no avail.

“I just wanted to keep him alive. I just held onto him as tight as I could,” Mr. Vento said. “Every time we tried to climb up on the ice it broke.”

The father and son had joined other ice fishermen and riders on the ice Sunday evening. They wanted to take a quick ride on their snowmobile before the Super Bowl.

Within five minutes the ride morphed from an enjoyable time on the snowmobile to a harrowing ordeal.

There was an old ice fishing hole cut near the snowmobile. Mr. Vento saw water bubbling. Mr. Vento, who has been snowmobiling for more than a decade, tried to cut the wheel away from the hole. It was too late; the ice gave way.

“It didn't even crack. It just gave out,” he said.

Grafton police received a 911 call about 5:30 p.m. from Jessica Zaleski reporting that a snowmobile had gone through the ice on Lake Ripple behind Bernard Road, Grafton police said in a news release.

Officer Dan Wenc was flagged down by Mrs. Zaleski near the scene, and she showed him where the accident occurred. Her husband, Roger Zaleski, was out on the ice trying to reach the Ventos.

Mrs. Zaleski said she had heard a snowmobile driving on the ice. Then she and her husband heard the sound of the snowmobile stop. The Zaleskis checked the ice and saw the two riders had gone through the ice.

Office Wenc grabbed a life ring buoy and rope. He saw the father and son.

“Both were struggling to stay afloat and get out of the ice,” police said.

Mr. Zaleski was about halfway out on the ice trying to reach the father and son. They were about 50 feet from shore. Officer Wenc went onto the ice and threw the life ring buoy to the Ventos. Grafton Deputy Fire Chief Michael Mills and Firefighter Brett Mills arrived to assist.

The two victims grabbed the buoy, and the officer, deputy fire chief and firefighter began to pull them to safety. They were able to pull Colby out.

Firefighter Mills moved out onto the ice as Mr. Vento struggled to get out of the water, police said. The firefighter and other personnel found a canoe and used it to pull Mr. Vento out. The father and son were in the water for 10 minutes.

“They (police and fire officials) were running, trying everything they could to help us,” Mr. Vento said. “If they hadn't shown up when they did ...”

He lauded the Zaleskis for hearing their screams and calling for police.

By the time police and fire officials freed Mr. Vento, he was spent.

“I had no strength to kick and stay above water,” he said. “I was shaking so bad.”

The 1993 snowmobile that Mr. Vento just restored was under the water. At the hospital Sunday, Colby just wanted to see his father.

“We're doing good. We're still a little shaken up,” Mr. Vento said. “We're just glad we got out alive. He knows I was there to protect him.”